Certain quinoline carboxylic acid derivatives are known in the art as having anti-bacterial activity. In particular a quinoline carboxylic acid specifically defined as 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid is known in the art as an anti-bacterial agent and is known particularly as AM-715 a new nalidixic acid analog. This particular compound is described in "Anti-Microbial Agents and Chemotherapy", February 1980, page 103 to 108, Volume 17, No. 2. In that article the compound AM-715 is described as having a broad spectrum of anti-bacterial activity against gram-positive and gram-negative bacteria, and that the anti-bacterial activity of AM-715 was greater than those of pipemidic acid and nalidixic acid. AM-715 has very low water solubility at the most normally used pH range of 6-10. Also it is very soluble in acetic acid but rather insoluble in solvents such as acetone, ethanol benzene or ethyl ether, and it has a rather slow rate of dissolution. Thus it is imperative in this field to discover a pharmaceutically effective derivative of quinoline carboxylic acid which is a better solubilized compound to allow more quinoline carboxylic acid compound to be introduced into the blood stream of a human to counteract bacterial infections which this particular compound is good against.